Spectrasonics Imaging, Inc. proposes a Phase I effort in collaboration with Riverside Research Institute (RRI) to develop a real-time ultrasonic system for indicating regions of the prostate that are suspicious for cancer. Real-time images produced by the system will enable better guidance of needle biopsies. Current ultrasonic guidance of biopsies has an unsatisfactory sensitivity and specificity for prostate cancer. As a consequence, the great majority of prostate biopsies are negative, and may of them are falsely negative. Studies by RRI suggest that the Spectral- Parameter Imaging (SPI) methods underlying the proposed system can improve detection of prostate cancer by 50%, which could detect 150,000 additional cancer annually in the US, reduce the need for repeat biopsies, and permit earlier initiation of treatment. Because RRI's studies are performed in a research setting, achieving the apparent potential of SPI for prostate- cancer detection requires 1) validation of the SPI methods in a clinical setting using a real-time imaging system, and 2) widespread clinical dissemination. The proposed SBIR study seeks to take these steps by developing a real-time imaging system that uses color encoding to depict suspicious regions of the prostate. This color-encoding will be based on spectrum analysis of ultrasonic rf echo signals. We anticipate that biopsy efficacy can be markedly improved through increases in the sensitivity and specificity of such biopsy-guidance images. This proposed Phase I effort will seek to 1) identify the optimal implementation approach for real-time tissue-type imaging, 2) interface the SPI technology with "host" B-mode instruments, 3) formulate PI system specifications, and 4) plan Phase II prototype-construction efforts. Proposed commercial applications: Over 1,000,000 prostate biopsies occur annually in the US alone. Approximately 70% are negative, and over half of the negative biopsies are false. Repeat biopsies have almost the same incidence of positive biopsies as initial biopsies. Unnecessary repeat biopsies and missed cancers impose an enormous dollar cost and patient risk. The proposed SPI methods appear capable of improving cancer detection by 50%, which should make SPI very attractive commercially and valuable medically.